[sdiy] Thanks Everybody!

[Gene Stopp]

Years ago I made an analog shift register exactly like Grant describes. I
used a bunch of cascaded LF398's, and a TTL demux chip with selected outputs
going to the sample trigger inputs of the S/H chips. The demux was driven by
a counter that was clocked at a high frequency, and went throught the count
once and then stopped, whenever an external sample trigger came in. The
demux outputs were routed such that the last S/H was hit first, then the
second to the last, and so on, so the analog voltages would be passed along
properly front-to-back before the next voltage was loaded. It worked great.
Unfortunately this was done on a plugboard protoboard so when I was finished
I drew it up and then tore out all the parts and moved on. The schematic
lives somewhere in a dark file cabinet drawer in the garage behind a bunch
of bicycles, I'm afraid. That was back in the days when I made all kinds of
weird-ass modules just to see if I could figure it out. :)

Sometimes I wonder if I should make a module that has a power supply and a
protoboard on it, built in to the music setup instead of on the garage
workbench. I see in one of the Buchla pictures in the latest edition of Mark
Vail's Vintage Synthesizers that Don did this long ago.

Best Regards,

- Gene


-----Original Message-----
From: Grant Richter [mailto:grichter at asapnet.net]
Sent: Wednesday, April 10, 2002 8:01 AM
To: Cynthia Webster; Diy
Subject: Re: [sdiy] Thanks Everybody! 


An analog shift register is just like a digital shift register.

The values held in the memory cells are shifted down one position for each
clock cycle.

For analog, the memory cells are sample and hold circuits. They are arranged
in series so the inputs are the outputs of the previous stage.

You then need to generate a series of pulses, each slightly delayed from the
last. S/H 4 samples S/H 3, then S/H 3 samples S/H 2, then S/H 2 samples S/H
1 then S/H 1 gets a new sample from the outside world.

Building your own sample and hold is a bit silly in today's world. The LF398
chips are cheap, reliable and easy to apply.

You could still use the LM3900 pulse sequencer as shown in the schematic. It
is a little confusing because Arpad Benares didn't draw the + terminal of
the LM3900s.

Rex tells me Serge became so overwhelmed with telephone calls expecting free
training with the modules, that he had to change his name to Arpad Benares
so he could honestly say Serge was not there anymore.

I am sure Arpad Benares is an anagram, for example, Arpad could be an
anagram for DARPA (Defense Advanced Research Projects Agency).

> From: Cynthia Webster <cynthia.webster at gte.net>
> Date: Tue, 09 Apr 2002 22:57:04 -0700
> To: Diy <synth-diy at dropmix.xs4all.nl>
> Subject: [sdiy] Thanks Everybody!
> 
> I am always amazed at what a Great Group of people this is!
> 
> Thanks Everyone for such great help in this research project!
> 
> Jim has offered to send me xerox copies or scans of the
> Synapse Magazine article that (I believe) Serge himself
> wrote back in the 70's
> 
> Several of you also sent the URL for Jurgen's version of the circuit
> (a little scary to me actually, many strange devices I've never seen)
> 
> and Grant actually emailed the Synapse schematic and parts list to me!
> 
> Thanks!  You are all just so unbelievably kind!
> 
> I'm still hoping to get a copy of the actual TEXT from the Synapse article
> if anyone is able to send it.  It will explain a lot to me, as
> I would like to learn more about the circuit by reading text -
> instead of simply aping the circuit - without understanding it more.
> 
> I'm hoping to build a series of "musical engines"
> yes, with four, six and eight-cylinder versions,
> (maybe even a "turbo" later) LOL!
> 
> An Analog Shift Register for control voltages would be at the heart
> of this, along with a voltage-controlled clock.
> 
> It's sort of a compositional automation scheme of sorts, part Universal
> Event Generator, Part arabesque pattern generator, Surround Sound Panner,
> and sequencer all rolled into one.
> 
> I'm still playing with ideas, but anyone who is interested can see
> sort of what I'm thinking about in the files section of the site for the
> Yahoo Modcan Group...
> 
> http://groups.yahoo.com/group/Modcan/
> 
> I think one might have to sign-up to get to that section of the site,
> but see (if interested) if you can go in directly to here:
> 
>
http://groups.yahoo.com/group/Modcan/files/Cynthia%27s%20%22Wishful%20Thinki
> ng%22%20%20/Six%20Cylinder%20MusicEngine00a.jpg
> 
> Like the wonderful Universal Event Generator, and the Mikado project
> this musical engine thing is striving for something a bit different.
> 
> I certainly appreciate all the kind help and feedback from everyone here!
> 
> Warmest Regards!
> 
> Cynthia
> 
> Hey Pete - What about Apex? (We're even)!  "Electric Music?"  Sheesh!
> 
> 
>